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Harperdog writes to this "Excellent piece by Dawn Stover about what renewables can and can't do. The sun and wind may be practically inexhaustible, but 'renewable' energy isn't. Solar, wind, and geothermal power are not fundamentally different from other energy technologies that consume finite natural resources. Good reading for anyone who thinks they know how to combat climate change."

Solar panels would not surprise me -- semiconductor manufacturing is not exactly eco-friendly. As for wind turbines, I cannot help but think of the kid in Africa who built them out of recycled auto parts.

Really the question is, are these things better on the whole than fossil and nuclear fuels? I suspect that the answer is yes, although I am not an expert. Only people who live in shacks in Montana are seriously arguing that humanity can or should live without disturbing the environment at all; but we can at least try to not completely wreck the planet.

You can argue that making and charging EV's just shifts the problem downstream to the power plants, many of which are coal-fired, but having all of the pollution more localized still makes a difference in the environment and quality of life.

Just sucks to be you if you happen to live near a coal plant or an unsafe nuke plant.

Although the thermal plant might have more efficiency, depending on the level of NIMBY, the transmission losses and the overhead of maintaining base-load for the electric grid may make the actual net efficiency closer than anyone may like... Sadly, reality is a must-satisfy condition in this analysis...

And driving massive tanker trucks full of gasoline all over the the country, tearing up roads, to deliver fuel to gas stations is efficient?

Although the thermal plant might have more efficiency, depending on the level of NIMBY, the transmission losses and the overhead of maintaining base-load for the electric grid may make the actual net efficiency closer than anyone may like... Sadly, reality is a must-satisfy condition in this analysis...

Baselaod: the load you always produce (regardless of demand), basically the minimum power you feed into the grid. This has no "overhead". People who don't know what baseload is, just should stop using the word, like they should stop using words like "law of thermodynamics", kosher, halal etc.

A electric engine in a car has an efficiency of 95% - 99%.Transmission losses in power grids are roughly 7% -8%.A thermic power plant has an electric efficiency of roughly 42%.Lets assume a battery charge station has an efficiency of 80%, then an electric car fed from a thermal power plant puts roughly 38% of the "thermal" energy produced in a power plant down on the road as traction.

Now, a combustion engines has an efficiency of roughy 20% (usually less). A car run by that has to take into account: minus transmission losses, catalyzer (yes, that one eats fuel, about 2% - 5% of your total fuel amount).

So bottom line with counting storage in the car and losses on the power grid an electric car is roughly twice as efficient than a car run on hydro carbones.

Soooooo how would look that if the power grid was fed with wind and solar power?

Suddenly the electric car is 4 to 5 times as efficient than a car burning gasoline. In fact it makes no sense to compare them anymore as the term "efficiency" becomes meaningless when you don't have to burn fuel.

Analysis HAS been done. To use electric cars as an example, a well-to-wheels analysis using a mix of power sources, electric cars emit half or less CO2 per mile driven over gasoline powered cars. A good number to keep in mind is that just the refining of a gallon of gasoline uses a little over 7 kWh of energy... 7kWh can move even a mediocre electric car 20+ miles. Don't forget to include THAT in your efficiency calculation either!=Smidge=

Nuclear power is not really renewable -- eventually all the uranium and thorium on Earth will be mined, and then we will need to start finding new sources of energy (or mining celestial bodies). I think nuclear power is part of the answer, but on its own it is not enough.

I used to be a big fan of wind, but I am starting to lean in the direction of (properly managed) biomass these days, for the following reasons:

Terrain that could not otherwise be farmed for food can be put to use

Existing coal plants can be converted at relatively low cost to use biomass power

The ashes can simply be spread on the biomass farming areas to replenish minerals in the soil (compare to coal ash, which cannot be used in this way)

If properly managed, it is carbon-neutral or nearly so (on a reasonable timescale)

Uranium is incredibly common and existing stocks can be rotated in. Typically nuclear plants only use 1% of the available energy in a fuel rod before swapping it out. Some plants are now recycling the older rods from 25+ years ago but few stations overall are capable of doing this.

not 1%, more like 14% of what can be extracted. But yes, the point is most of our "spent fuel" is a gold mine of energy. And we have thorium sufficient for centuries while we figure out fusion or just massive solar harvesting coupled with biotech so we grow what we need instead of refining and smelting.

I'd rather have reactors that can't possibly melt down. we invented those over 25 years ago, but still use gen I and generation II designs which are inherently dangerous, need constant cooling for months even after shut down.

I like Nuclear Power, but it has a massive problem if it's poorly managed. Even just one cock-up can cause a major problem.The fear is justified, since If I know anything about the Human Race, it's that we can grossly mismanage things.

This is not true. Unless you live in an anarchy dominated territory, like somalia, you really cannot "live like they do" without violating several laws, including tax evasion.

Say for instance, I quit my job and packed up a knife, an axe, a tent, and some various other sundry items, then headed west into the large expanses of BLM owned forested wilderness:

Unless I sell all my properties first, and liquidate all my accounts, and sell my vehicle when I get there, I am guilty of tax evasion. (Property taxes, vehicular taxes, income taxes.)

Then, upon arrival, should I set my axe against the BLM owned forest so as to build myself a survival structure and to start a cooking fire, I break several more laws.

Illegal poaching, destruction of public property, endangering public property, building without a permit, creating a permanent structure that does not meet building code... (you get the idea.)

Simply put, what you suggest as the baseline comparison is not legally permitted in countries where there is an energy problem, and is actively discouraged by the governments of those countries which do.

This is why it is absurd to demand such measures from people wanting reform in energy production. If they are hipicrites for wanting such while consuming dirty energy, it is because they are forced into a legal catch-22 where there is no legal alternaative. Asserting that there is such an alternative without first getting said power production reform to enable its use is downright disingenuous.

The massive problem is the long term cost of decommissioning. I was at primary school when they started decommissioning my local nuclear plant [wikipedia.org]. I'll be dead by the time they've finished..... That's one hell of a burden we are placing on our grand children.....

Fine, but nuclear is NOT environmentally neutral!! you forget that nuclear generate nuclear waste that take thousand of years to read safer levels and even in a mine are dangerous, water can enter, spread to the floor to the water fields and back to the human contact...

Also, a single big nuclear "leak" might produce more "pollution" than any of the other options... as history shows, nothing works without problems, accidents or evil doing can happen.

On the contrary, I would argue that the problem with nuclear power is that, as is becoming increasingly clear, people's fears about it are *justified*. The current installed base of nuclear tech represents an enormous and unsolved long-term problem to produce what are, on a historical scale, very short-lived benefits. We should not be creating any additional problems for our posterity to deal with.

But the fear and NIMBY are directly caused by the nuclear industry's crying of 'no-wolf' turning out to be untrue. Now they are crying 'no-wolf' again, and asking us to trust them. They have a credibility problem so sever it likely cannot be solved until the impacted generation passes on.

Fukushima and Tchernobyl come to mind of course. Do you realize that making an area like (40 miles)^2 unusable amounts to not a small cost on the economic point of view, or ruining the lives of 10'000's of displaced people is not a small nuisance?

Presently nuclear energy is the energy method having the largest impact in the far future (~100'000 years), as the nuclear wastes will require to be watched for a long time. Do you realize that such a timespan is comparable to the total time homo sapiens existed on Earth? (The salary of a single engineer over 100'000 yr corresponds already to the total building cost of a nuclear plant).

Can you imagine what will happen when the next global war occurs? And it will occur well before a century for sure. Each nuclear power plant will be an easy target, at the least a serious menace for those countries foolish enough to have forgot how stupid and nasty human beings may be.

The water in the reactor loop just keeps on going around the loop without getting released, barring a rare leak, and isn't a huge volume of water anyway. It's expensive water because it's been treated with a lot of chemicals to remove anything that is going to corrode the pipework. The same holds for the water in the turbine loop - that doesn't get thrown away either. For the same heat output it really doesn't matter if it's BWR, PWR, molten salt or even non-nuclear as far as water consumption goes.The huge amounts of water required is a consequence of the advantage that nuclear power has over other forms of thermal power generation and you can't really use less without giving up that advantage. That advantage is the high temperatures and the large temperature difference that give you. That means a lot of cooling so you need a LOT of water available. That's really just a siting problem and only limits where you can put the reactors because the water isn't actually lost - just heated up. With a large river, lake or on the seashore the used cooling water can be released in such a way that it makes little difference.

Wind turbines are mostly built in the West. This isn't simple tech to build, and even a small deviation from norm may cause much harsher wear and tear. Incidentally, most of the costs of wind turbines aren't in making them but MAINTAINING them. As a result, skimping on manufacturing costs at the cost of increased maintenance makes no financial sense.

This is exact opposite of most consumer products, where we largely gave up on maintenance because it's more costly then buying a new, made in [poor country on s

Well, I looked into the amount of water an equivalent coal-powered generator would use. It turns out 1GW of coal power uses 13500 acre-ft of water (4.4billion gal) per year, vs the 600 acre-feet for the solar project.

Really, the question is, are we ready to adapt to a more expensive, less available energy future? I suspect that we won't have a choice, but that people will cling to the old ways as desperately as people always have.

We already are doing that, in a small but increasing number of ways.

We insulate our houses, to save heating bills.We look at the fuel economy when we're choosing a car.We use energy saving lightbulbs.We have showers instead of baths.

Really, I feel that if governments stopped striving to keep the cost of fossil fuel down, this natural adjustment would accelerate. Whether it's ways of reducing our energy usage, or better ways to get clean/renewable energy, or somewhere inbetween, I don't really mind.

Unfortunately the article glosses over the fact that far more of those expensive and [s]potential[/s] actually hazardous materials are required to make carbon and nuclear based power generating stations. It also glosses over the lifespan of those products vs their counterparts (largely because no one bothers to collate the data on all the replacement parts that need to go into existing stations). The argument has never been that these solutions are perfect, nor infinite. The argument for green tech is that it's better overall and more sustainable than what we're currently doing.

I think the real point is that we're fucked. Yes, fossil fuels and nuclear are worse, but wind/solar/biomass/geothermal won't save us either, for the same reasons. Although each individual installation may not be as environmentally or economically detrimental as a fossil fuel or nuclear installation, the fact that you have to have so many more "renewable" installations to meet the same energy needs counteracts that.

The takeaway from this article is that we have to change our energy needs and growth model. There's simply no way to continue down this path, no matter what "green" technologies are developed. Energy isn't free. Energy production has side-effects. The only real solution is to use less and less of it.

I don't think we're fucked just yet, we're close. Personally I think the energy debate is moot - market forces have and will determine where we get it. The real debate should be about food and water. We're headed for a very serious collapse and globalization has created conditions where the second there are food shortages, protectionism is going to rear it's ugly head and there will be massive starvation in some areas. Canada already experienced this in a small way, no starvation obviously, but when Katrina hit food shipments were diverted down south instead of to Canada - many shelves were empty for weeks.

This is a bit of doomsaying more then anything else. Burning technologies (for large plants, talking around 200MW per boiler) have really advanced with modern automation. Did you know that one of the biggest annoyances when burning things, SO2 has been largely eliminated in most modern plants that burn... pretty much anything by extreme control over the burning process? In other words, you don't even need complex filters on those anymore, the advances in the burning process itself due to computerization have made processes much less harmful to environment. This is why we talk so much about CO2 and so little about other products of burners - when we used to talk about those other products all the time before. Because the new plant technologies have virtually eliminated most of those, and those that remain are usually rendered harmless by solidifying them on the plant and not allowing them to spread into environment.

Add to this the fact that we can in fact burn what we grow (biomass), then consider that nuclear is pretty efficient and safe and we have enough uranium and thorium for at least a millenium... we're not so fucked anymore. At least as long as we can develop fusion into workable system in a few hundred years. The only real problem that remains is upgrading the existing burner plants before they shit all over the environment with really toxic stuff (which is what is happening in China at the moment) as well as upgrading nuclear to more efficient and safe plants.

Unfortunately the article glosses over the fact that far more of those expensive and [s]potential[/s] actually hazardous materials are required to make carbon and nuclear based power generating stations.

Unfortunate but not surprising in an article published by the Bulletin Of the Atomic Scientists.

Coals plants also need to be built, they also need generators that require rare earth elements, they also need plenty of steel and concrete. And not only do they obviously spew shitloads of CO2, you also need to build the roads, railways or ships and ports to carry the coal around, as well as mine the damn thing.

So what is the argument? That since it's just merely much better, and not simply perfect, we should just give up on them?

Lets see. Coal. Expensive to mine from underground and a blight on the load in open mines. Nuclear material? Same issues with mining it and that love waste to get rid off. Oil? That is running out and drilling for it has proved hazardous. Mining it from tar sand is even worse then coal mining and even just transporting it ain't save.

Funny the article doesn't mention any of that. Or for that matter that efficient generators ANYWHERE need rare earth magnets. In the end, almost all power generation needs the same kind of generator, the only difference is what makes them spin and how efficient you want them to be.

And yes, desert water is not infinite... Greenland is a desert now? Funny. I expected them to be warmer. And less wet.

Troll article cherry picks arguments to support its troll and ignores everything else.

Or for that matter that efficient generators ANYWHERE need rare earth magnets. In the end, almost all power generation needs the same kind of generator, the only difference is what makes them spin and how efficient you want them to be.

Large central station generators (actually alternators...) have been achieving 98 to 99% efficiency for several decades now using copper and electrical steel (no Neodymium). A larger rotor allows for more copper, which reduces the percentage of the alternators output power needed for generating the field. With a wind turbine sized alternator, the power required to maintain the field can approach 5% of the rated output, hence the use of permanent magnets (especially since the turbine is rarely producing rated output). Also note that making concrete for the foundations for the wind turbines does involve a lot of CO2 emissions - look up cement kilns.

FWIW, the NdFeB magnet material was originally developed at General Motors.

But comparing a Hummer and a Prius is completely insane and can only lead to biaised results.

So how does that differ from suggesting solar power is only possible with photovoltaic panels or desert groundwater steam turbines?
Or that California's geothermal power is typical of all world installations and other types like HDR don't exist at all.
Or that the only possible type of wind turbine to use is the type installed in the US in 2009, ignoring newer tech like the blade tip generators (http://www.windtronics.com/honeywell-wind-turbine)
Or that Biomass is anything but another form of solar.

1. Someone else wrote a paper called "Dust to dust" that claimed the lifetime energy cost of a Hummer was less than that of a Prius.
2. The "Hummer vs Prius" author disputes the "Dust to dust" paper's conclusions because they used arbitrary figures for lifetime mileage, energy used in manufacture, and so on.
3. The "Hummer vs Prius" author claims a quick recalculation shows the lifetime energy cost of a Prius is, indeed, lower than the Hummer.

The wikipedia has this to say about the Prius battery: "They are normally charged to 40–60% of maximum capacity to prolong battery life". As such, they don't reflect the lifespan of a battery that will be fully recharged after each use.

You mean the battery in my Prius that's still going strong after five years? The Prius that has more cargo space than my old Jeep and can hold four people as opposed to the Jeep's two (four if you cut off two peoples' legs)? The Prius that gets me fifty miles to the gallon because I take the highway to and from work?

Your prius gets 50mpg? Well that's not bad, should I tell you that I just finished driving nearly 5000mi, in a '96 saturn and got around 49mpg on the highway. Yep, a car that's 15 years old, getting nearly the same performance.

To be fair, the original Prius (Gen I - 2003 and older) batteries are starting to fail fairly regularly now that they're pretty old. But replacing them isn't that expensive - best bet is to replace the pack with a refurbished pack and send your old one back to the refurbisher to salvage the usable parts and recycle the rest. Many opt to refurb the pack with the cells from a Gen II (2004-2009) pack which are more robust and perform better.

Gen II Prius batteries are much more robust than the Gen I batteries - the occasional pack still fails here or there (usually because of a weak cell, not because the whole pack fails) but even then the best route is to replace the pack with a refurbished unit for half the price of a new pack.

There are shops that specialize in this (like Luscious Garage [lusciousgarage.com] - their blog has lots of info on what normally goes wrong in hybrids as well as how well they hold up under taxi use), though the best shops tend to be in locations where there is a high concentration of hybrid vehicles.

All that said - one doesn't need to worry about hybrid battery failure - in their best selling states (CARB states) the batteries are warranted for 10 years / 150k miles. You can be sure that the manufacturers have engineered them to hold up for at least that long - frequently replacing batteries that fail certainly isn't good for business.

I believe the word you wanted looks more like "recycled". People don't just toss 99% recyclable $3000 batteries like they do with a pair of dead double-As.

A 67 Camaro is better than a Prius, even 44 years later it is still desirable, people will still fix them

A 67 Camaro gets 15MPG. A Prius gets 50MPG. After 10 years of typical (1k miles/month) use at today's gas prices ($3.50/gallon), keeping that "desirable" Camaro on the road will have cost you literally the price of a new Prius ($19600) more.

The word "better" can mean an awfully lot of different things to different people. I can't, however, find a way to use it to describe something more expensive, less safe, and with fewer features - Other than the dumb nostalgia of "I wanted one as a kid and can finally afford it 40 years later".

And for the record, I don't own a Prius. I most certainly will, however, as soon as my current car dies.

For a given power generation capacity, there is no intrinsic reason why the energy cost for building windmills / solar cells should not be a fixed ratio of that of building coal plants. Maintenance costs for wind/solar are very low, but even if you don't believe me on this one, ask yourself, again, whether coal plants require no maintenance -- they do.

After that, solar/wind cost nothing in energy, while coal plants need to be fed coal, that also has to be transported.

I think that the point is that they all require maintenance, but that once started up, the solar and wind don't require mining, transportation of fuel, or environmental cleanup just by operating, while solar and wind just require machinery maintenance.

There is a pretty awesome "new technology", and it was discovered a few thousand years ago -- it's called "humans not reproducing at a disgustingly unsustainable pace with the apparent goal of destroying the world as quickly as possible."

The author, by failing to mention the current oil-based energy strategy at all, while vilifying the alternative energy sources leaves the reader with a sense of, "the alternatives are bad, lets keep using the current infra until we come up with something better." Interestingly, nuclear energy is *not* mentioned either, positive or negative - it's completely omitted.

I'd not be surprised if the author was either a shill for the oil and gas companies or the nuclear energy affiliates.

This is an article from The Bulletin of Atomic Scientists (http://en.wikipedia.org/wiki/Bulletin_of_the_Atomic_Scientists).
In the 50+ years that they've been publishing I bet they're sick of talking about nuclear (power, weapons).

I disagree. He's clearly a neo-Malthusian arguing for population limits, calling for a " in which energy demands do not continue to escalate indefinitely" and highlighting California's expected population growth and how "There are now seven billion humans on this planet" before saying that we need "a way to reduce our energy consumption and to share Earth's finite resources more equitably among nations and generations".

He does mention that "renewable technologies are often less damaging to the climate and create fewer toxic wastes than conventional energy sources." Are those the words of an oil-industry shill, or someone who cherishes the status quo?

You note that "nuclear energy is not mentioned". But look! This is published in "Bulletin of the Atomic Scientists". The front page will supply you with nuclear-power reading if you really want it.

I remember being taught in school (which was some years ago now, and I'm too lazy to google it right now), but doesn't Iceland have several geothermal plants, which the by-products (heated water/steam) then go on to be used to heat nearby homes and provide hot water?

It's not really "lost", though. It just gets out of your local closed system and back into the global environment. If you just let all the steam go, it will float off into the atmosphere until it gets cold and all the little molecules start to miss their friends.

There's currently about 5cm an hour of the result coming down all over NW Scotland.

OP seems to be a compendium of old FUD I've read before. Yeah sure, solar panels have a limited lifetime -- about 25 years, by which time the next generation of them will make twice or more as many panels from the same amount of materials harvested by recycling them. Oh dear, solar sites need to wash panels, they'll never figure out how to make dust-resistant coatings, of course. OMG wind turbines use a lot of Nd (using the worst case of a direct drive unit) so naturally it follows that that's the only way to do it and we won't be switching to Separately Excited Syncronous or Switch Variable Reluctance gensets when it becomes cost effective to do so.

I'll be glad when these clowns finally sell their Exxon stock so I don't have to listen to them whine any more in the face of the inevitable.

The point is that the whole shameful article is a cesspit of incorrect arguments, and that the author either has no knowledge in the field at all, or is biased - most probably both.
- Photovolatic: the most important component of photovoltaic panels is silicon. It's one of the more abundant elements on earth. One can cover all landmass on earth with photovoltaics and still not run out. There are dopants in there that are less abundant, but only small quantities of them are required. Also, organic (as in carbon-based) photovoltaics are on the rise, which don't need said dopants. Also, at the end of the lifetime of a silicon-based panel, the silicon and dopants get recycled - they are way to valuable to throw away.
- Thermal solar energy and geothermal power: (cooling) water requirement is equivalent to current thermal technologies (nuclear, coal, gas,...). Also, in the case of geothermal, one could make a closed-cycle plant; this would work especially well in colder climates.
- Wind power: all electrical generators (except photovoltaic) contain magnets, so the argument goes agaist conventional energy as well. Also, the term "rare earths" is historical - we now know they are not really rare in the earth's crust.http://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth's_crust [wikipedia.org]
For instance, Neodynium is more abundant than for instance lead and tin. The problem with it is that it's hard to purify from natural deposits, so the annual supply is limited. Luckily, permanent magnets can be made from all kind of other materials, including abundantly available ones. The resulting generators will be somewhat heavier and less efficient, so it's currently cost-effective to use Neodynium, but if the price goes up, the industry will just switch to something else. Finally, these magnets are not consumed, they can be (and are) recycled or even reused in their original form.
- Biomass: this is not my personal favorite, but even so, the article is overly gloomy about it. The surface used for biomass is not lost forever - it can readily be re-purposed for agriculture once it's needed (or better energy-producing technologies become available). Also, a lot of agricultural land is being used for growing animal fodder, which is quite a wasteful business; if we would just stop eating those excessive amounts of meat that are a contributing factor to the current heart disease epidemic and eat a bit more vegetable protein sources, we could easily feed ourselves from half as much farmland (and still get more than enough meat to eat for a healthy and enjoyable diet). Also, at some point, technology might become available to grow excellent animal-free meat in bioreactors, which would make meat production way more efficient.
- Hydropower: just like silicon, the supply of concrete and steel is nearly inexhaustible. Yes, CO2 is emitted during the production thereof, but it's a tiny fraction of the CO2 that would be emitted when matching the lifetime energy production of the dam using fossil fuels. Also, building nuclear power plants also requires large quantities of concrete and steel (and given the current safety debate, they're still not using enough).

I'm sure there's more fallacies to be found in the article, but again, the point is that the author is either a nitwit or terribly biased (presumably both).

Do not let anyone tell you this drivel.
"Solar, wind, and geothermal power are not fundamentally different from other energy technologies that consume finite natural resources"
BS! BS I say!
Check out www.thevenusproject.com

At our current energy usage growth rates, the planet is the temperature of boiling water before 2500.

This has nothing to do with global warming. It's just a fact that as you use energy, it flows into the environment. Just like a 100 watt lightbulb also warms up the room, 7 billion people worth of devices releasing energy warm up the planet faster than it can radiate the heat into space.

Sure materials which we need to use in order to build e.g. wind turbines are theoretically finite. They are not being used up by building wind turbines, they can be recycled if that's economically interesting. Stuff like "While sunlight is renewable -- for at least another four billion years -- photovoltaic panels are not." is just silly. We are not going to run out of sand in any plausible scenario, so that's just nitpicking.

In any case, renewable energy refers to the energy source. That clearly sets it apart from other energy sources, and is thus a good description. There is nobody who believes the installations required to use renewables can be build without any environmental impact in terms of pollution, area use etc. That doesn't distinguish them from other installations. If people were calling renewable energy plants "impact free", fine the author would have a point. The myth the article is debunking is one which doesn't exist, however.

Interesting that the summary doesn't mention that TFA is published in the Bulletin of the Atomic Scientists. Which is a quote respectable group; but nevertheless, they have a horse in the energy race, one that burns Uranium. TFA simply counts the cost of various "green" energies, but never compares them to the costs of "conventional", or nuclear, energy generation. You're left with the impression that "green" energy is a shill, that all forms of energy are equally bad, and so you might as well sit back and keep burning oil and coal until someone invents perpetual motion.

The Bulletin of Atomic Scientists is NOT a nuclear power advocacy group. It was founded by former Manhattan Project scientists as an anti-nuclear weapon advocacy group in 1945 in order to bring public attention to the dangers of nuclear arms.

They are probably most famous for the Doomsday Clock.

More recently the BAS has increasingly focused on explaining the dangers associated with nuclear power.

Published in The Bulletin of the Atomic Scientists. Can't see any agenda there...

She doesn't exactly cover herself in glory for facts, either. She doesn't appear to know what neodynium is used for (why, exactly, would you want magnets in a gearbox?). She (quite deliberately, I think) confuses consumable fuels with non-consumable equipment - a turbine may need 800 pounds of neodynium, but after 20 years of operation you've still got 800 pounds of neodynium. In fact the whole magnet is reusable as is. Today's largest wind machines are 10MW (in construction, anyway). 4.5 million of them would (on average, not peak capacity) provide the entire world's energy use - not sure where her need for an additional ~2 billion devices comes from.

Of course it's not infinite - nothing is (probably) but that's not really the claim, is it? The only sensible point made is that renewable sources require materials that are finite, but I think we knew that already.

A great deal more austerity. However, it makes a rather weak argument about a very real trade off problem, that problem is the water-energy trade off problem. In almost all forms of energy generation, it is not usable energy that is created directly, instead, heat is generated, the heat is used to do work, and the work is used to store the energy. So, the classic steam turbine has water heated to gas, and the resulting steam spins the turbine, and that carries wires through a magnetic field, which generates a corresponding electrical current, and that current is sent down wires. Another water energy trade off is to have wind turbines pump water up a shaft, which then is allowed to fall, spinning turbines, when power is needed. Bio-fuels, the same way: water is used to grow plants, the plants fix sunlight into hydrocarbons.

The solution to the water energy problem is more energy, because energy can be used to get water. This, however, lowers the Life Cycle Output of the energy system. LCO or LCA is the expected usable energy out, divided by the expected usable energy used to create and run a system. So if a system produces 10 watts for every watt it takes to build, run, and dispose of it, then its LCA is 10. The 20th century got by on a miracle: namely petroleum has a high LCA, and its its own storage mechanism. Gasoline has great power to weight storage capacities with internal combustion. And internal combustion engines can be built of very cheap metals. There are many quandaries in replacing hydro-carbon energy, and the water energy trade off that the piece mentions is one of them, but it is one of scale. Once there is a large enough renewable base, then the low LCA that getting the water to run it has, is not a problem. It is at the beginning, when the return is eaten through by the water problem, because there are competing uses for water that have much higher economic returns in the short run, such as airconditioning and agriculture. None of these uses want to pay much higher rates for water so that people not yet born can have the advantages.

Where the article falls down is pressing an agenda, and making sloppy equivalences. The first is equating capital requirements with expendable requirements: we don't burn the rare earths we use in kinetic energy extraction – that is water, wind, and geothermal – and in fact, rare earths, are not, as a percentage of the earth's crust, all that rare. For example, wikipedia has this chart [wikipedia.org]. It shows that all of the Lanthanide rare earths, plus scandium and yttrium, are more common than either gold or silver, many are more common than tin, and some more common than lead. The problem with them is that they tend to be found near the Actinide rare earths, particularly Thorium. If you have seen a press for "Thorium reactors" it is because exploitation of rare earths leads to Thorium by product, and reactors which burn it would be fantastically profitable, for the people who sell the rare earths. In reality, they have the same problems, only more so, of actively cooled salt reactors. Namely, they work until they blow up. The Chinese dump their Thorium in a holding lack, which, should it break, would contaminate large areas of land and volumes of water.

Side note: how is it that a browser's spell check doesn't know Actinide?

But for all of that, rare earths are not burned, the way for example Lithuium is not burned in a battery and can be recycled. These are recyclable, which is different from consumable. Hence moving from consumption of hydrocarbons, which really are burned, to using rare earths in capital energy, is a positive step, and while the author of the paper implies that there would be rare earth shortages, the reality is that this is not the case, and substitutes in the form of ceramics and active magnets (See Rare Earth Prices Plunge as Manufacturers turn to substitutes [mining.com]

If we burn coal, we still have carbon and oxygen just in a much lower energy state. We can't get that back without spending at least as much energy as we got out (in reality a lot more), which would defeat the whole point. Same with oil, gas and nuclear. So solar panels have a limited lifespan, but it's not like they disappear when they break down. Recycle them and make new ones, as long as you manage to get a net positive contribution of energy it's sustainable. The reason is of course that solar panels have an external power source while coal does not. Of course we have to design them to be recyclable and actually do it, but that's a matter of will and economics. But there's no way to do the same with fossil fuels, they'll never be sustainable because their energy is consumed.

It's obvious this person has an agenda as they don't take water recycling into account, whether within systems or within nature.

However, this deals with renewable energy as touted by big business. They make big huge systems that consume lots of resources so that they can sell them and make money. A passive solar house isn't going to use all these rare precious resources. Geothermal energy that is designed into the house going down 10 to 20 feet using convection isn't going to require the same massive resources that a huge power plant going hundreds of feet into the ground nor is there any fracking required. A personal wind turbine or hydro isn't going to need rare earth magnetics to squeeze out every drop of possible energy because energy use will already be reduced and you can just take the inefficiency of normal magnets/em into account when designing the system.

Besides the obvious slant of the article what we should realize is that large, centralized, hi tech renewable energy products are unsustainable. The way to go is smaller, decentralized, personal systems. Decentralization reduces the need for large quantities of any resource to be taken from any given area, making it sustainable. Is it a bother to have to wipe down your mirrors 2 or 3 times a year on your passive solar oil collection system, sure, but you won't need 600 acres of water in your back yard, just a damp cloth.

Unfortunately that involves designing tech that can be put together/serviced by your average joe and that simply isn't going to happen without government or industry help to educate the masses which won't happen because there's no money in teaching a man how to fish instead of selling him a fish everyday for the rest of his life.

Which is unfortunate. I'd love to see bamboo sand biofilm water filters with added activated carbon (provided by gov't/business) in homes for cleaning water instead of huge water treatment plants and plastic encased water filters that are non-renewable by the customer.(activated charcoal is renewable, if they let you get at it)

The problem is not so much with the technologies' themselves as it is people's understanding of the scale of them. For example Tom Murphy [ucsd.edu] explains that dropping the great lakes by 1m would produce 54 billion kWh. Compare that to the 2,000 billion kWh produced every year by coal plants [wikipedia.org]. My napkin math says we would drain the great lakes of their current supply of water in the order of years, not decades just to replace coal.

Since the people on Slashdot are mathematically inclined, try to calculate the physical area needed for solar panels to replace a nuclear power station near you. To replace the Pickering Nuclear Planet [wikipedia.org] (3.1GW) the oldest planet here in Ontario with solar assuming Ontario get the global average amount of sun light [wikipedia.org] (which is pretty generous for Ontario) and gets an average of 20% efficiency you get 250W x 0.2 = 50W/m^2. So, (3.1E9W) / (50W/m^2) = 62E6 m^2 or 62,000 square km, a box 8km by 8km of solid solar panels or a circle with a radius of 4.4km. That is approx 2% the size of the exclusion zone around Chernobyl. We are talking about building something 2% the size of the area we fenced off during the worst nuclear accident in history per nuclear station.

Most renewable source of energy are not very concentrated, so anything dealing with them has to be huge, it's inescapable.

It's a misleading hack piece. First, 600 acre-feet of water per year to run a 1000-MW plant is diddly-shit. For comparison, a unit-home consumes about 1kw (averaged over a month, give or take a factor of two) and one acre-foot/year of water. So a plant supplying enough power for a million homes, which themselves consume a million acre-feet/year of water, will add 600 acre-feet/yr of water to their consumption. Whoopie-shit.

Notice how no numbers were given for the geothermal plants and their consumption. The Geysers [wikipedia.org] were initially run from in-place groundwater, which they did consume (there was no condensation, no recharge). Now they are being recharged, NOT with groundwater, but with treated sewage water. So the article was misleading there, too, since groundwater is no longer the limiting factor.

She gives numbers for windpower resource consumption, but is again misleading. A "4-foot-wide, 7630 mile sidewalk". How do you suppose that compares to a single lane of interstate highway (12 feet wide) capable of carrying truck traffic? 636 miles of 4-lane interstate, NOT accounting for the increased road thickness. She repeats the "rare earth metals are rare" canard.

Neodymium [wikipedia.org]: "Although neodymium is classed as a "rare earth", it is no rarer than cobalt, nickel, and copper ore, and is widely distributed in the Earth's crust". She may be right about Dysprosium [wikipedia.org], at least with current magnet technology. It's not clear if it's necessary, or merely nice at current prices. Note that the current main consumption appears to be hybrid automobiles, not wind turbines. (Hybrid autos, not a good idea at present size.)

Her treatment of hydropower is similarly deceptive -- first dismiss newer technologies as "experimental", then hammer on the problems of (some) hydropower installations. Wave power [wikipedia.org] looks interesting. There's not too much that can go wrong with a buoy anchored to the bottom; we've got ample experience with them in their non-power-producing form.

All of the article lacks a good "compared to what" -- how much water and concrete are consumed by existing energy production? What resources do they consume?

I gotta see some backup for:"The gearbox of a two-megawatt wind turbine contains about 800 pounds of neodymium and 130 pounds of dysprosium "

I've worked on a lot of gearboxes and several turbine/generator sets in my career as an ME. The gearbox on a 15MW gas turbine generator might weigh 1/2 a ton total and I assure you that is 90% iron and 10% oil. I think somebody seriously slipped a decimal point or two.

In fairness, if the solar power plant is in the desert (where they often seem to be) where water is scarce, water used to clean mirrors is going to evaporate and fall as rain elsewhere, probably where water is less scarce.

However, it doesn't seem insurmountable. If it's really an issue, I'm sure one could design cleaning systems that minimise the amount of water lost - and the cost (both financial and environmental) of transporting water in trucks ought to be minimal compared to the power output of a large

... all extract wind energy. They interrupt the flow of wind and generate turbulence, and eventually turn wind energy into heat, except that unlike wind turbines they don't make electricity as well. It's a rather silly question when you know the first thing about thermodynamics.

Probably the biggest problem to addressing the 'population issue' is that the areas of the world where environment movements tend to exist tend to also exist alongside groups which love population growth.

Big cities like New York, Toronto, London... tend to have a lot of 'green movements'.Yet they're also places which keep advocating high immigration rates for both political reasons (diversity...) as well as special economic reasons (prop up the housing industry, cheap immigrant labor...). More often than not the same groups in the green movement are the same who love increasing population.

It's one of the reasons why things like pollution/Capita are tricky. A lot of people seem to think per Capita measures are the ultimate measure. But it doesn't take into account societal and cultural choices.

For example, we compare two societies.

1. A huge population like India where the consumption/capita is very low. (545 kg in oil equivalence)2. A sparsely population country like Iceland with high consumption/capita (17338 kg)

Now many who just look at the per capita measures like to rant how inefficient and wasteful western people are. Yet don't look at the per capita numbers alone. Look at the society as a whole.

Icelandic society provides a high standard of living for everyone and keeps its population reasonable. That each Icelandic person lives much better than an Indian is not a problem... as the Icelandic society has managed to keep its population small.

Put simply... is the solution to shove everyone in to a city and make everyone live like they're in Tokyo? Only for those who like to measure everything in per capita use and don't want to look at the greater functioning of society.